newbie question

[blackboxster]

I am new to this forum and have a couple questions, does anyone have problems with their boxsters drifting or roadwalking on highways or interstates at high speeds especially when roads are rough or have slight ruts in them, almost seems as if my car wants to fly off the side of the road, thought it might be alignment problems but car drives straight on smooth roads is this because its a light car with wide tires(factory size), Also do boxster exhausts usually make creaking and cracking sounds a few min. after shutting off when cooling down?
thanx for any replies and for the great forum!